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A sample of morphologically selected interacting galaxies has been chosen from the 60 μm flux density limited IRAS Bright Galaxy Sample [Soifer et al., ApJ, 320, 238 (1987)]. Using the HIRES algorithm [Aumann et al., AJ, 99, 1674 (1990)] and one-dimensional coaddition, the IRAS survey data for these galaxies were analyzed and the infrared fluxes at 12, 25, 60, and 100 μm for the resolved components have been determined where possible. Of the 56 potentially resolvable interacting groups, 22 systems have been resolved yielding fluxes for a total of 51 galaxies. In about 2/3 of the resolved pairs, both galaxies are bright in the infrared

High spatial resolution images have been obtained of the high-redshift (z = 2.286) IRAS source FSC 10214+4724 at wavelengths corresponding to the optical continuum and Hɑ in the object's rest frame. The continuum shows two clumps separated by ~1" (~10 kpc) and aligned approximately north-south. The structure appears similar at rest wavelengths of 0.38, 0.64, and 0.67 μm. The continuum morphology suggests two separate concentrations of luminosity, likely the nuclei of interacting galaxies, although a large galaxy bifurcated by an immense dust lane cannot be ruled out. The southern component is predominantly extended in the east-west direction on a scale of -0."5 (5 kpc), consistent with the position and elongation of the radio source reported in 1992 by Lawrence et al. The Hɑ emission is centered on the southern component of the galaxy and is unresolved with a diameter smaller than 0."4 ( < 3.5 kpc). A simple explanation for the current observations is an interacting system comprised of two or more highly luminous (~10^(12) L_☉) galaxies, one of which contains a dust enshrouded quasar that generates the bulk of the bolometric luminosity (~ 5 x 10^(14) L_☉) of the system.

Near-infrared images (1.3-3.7 microns) are presented for the nuclear region of Arp 220. Color maps in J - H and H - K reveal steep gradients, and the two nuclei previously detected at 20 cm and 2.2 microns appear on the J - H image as peaks separated by 1 arcsec. Hot dust emission (T about 1000 K) at 3.7 microns and extremely red J - H and H - K colors are found for both nuclei. The increasingly red color approaching the center of the galaxy are explained most naturally by a mixture of extinction and emission by increasing amounts of hot dust. The near-infrared emission is consistent with a circumnuclear starburst extending to a radius of about 1.5 kpc from the nuclei; further from the center the colors are consistent with a normal late-type stellar population. Inside a radius of 1 kpc the color maps show a NE-SW elongation that aligns with the concentration of molecular gas seen in CO images. The observed 3.7-micron luminosity, when corrected for nuclear extinction determined by 10-micron silicate absorption measurements and normalized by the bolometric luminosity, is consistent with UV-excess quasars and is about 10 times greater than that found in infrared luminous starburst galaxies.

Near-infrared imaging and spectroscopy of the extremely luminous IRAS source FSC 10214+4724 have been obtained using the Cassegrain infrared camera on the 200 inch (5.08 m) Hale Telescope. A low-resolution spectrumm (⋋/d⋋ ~ 100) in the 2.0-2.4 μm atmospheric window shows a very strong Hɑ line at the optically determined redshift z = 2.286. The observed rest-frame equivalent width of Hɑ is 0.07 ± 0.02 μm, consistent with the largest values found in quasars. The images show an unresolved source, while the near-infrared colors are somewhat redder than the mean colors of quasars observed at the same redshift. The reddening inferred is A_v ~ 1.5 mag, with an upper limit of ~ 3.0 mag. The observations presented here cannot distinguish between starburst and quasar models for this source. Starburst models require -10^(12) M_☉ of stars to have been formed over 10^7-10^8 yr. If FSC 10214+4724 is a quasar, the reddening-corrected bolometric luminosity is approximately equal to the observed infrared luminosity.

An investigation of coadded IRAS data is performed on 187 Markarian galaxies where distinguishing morphological characteristics or multiple optical nuclei are present. The far-IR properties of Markarian galaxies are compared to the IRAS Bright Galaxy Sample, and a much higher median dust temperature is found in the multiple nucleus galaxies, suggesting that more far-IR luminosity results from active star formation. Both optical/UV and far-IR selection techniques are necessary to extract complete samples of AGNs since the far-IR two-color plane can miss up to 50 percent of the galaxies. A systematic increase in the contribution of warm dust emission due to active star formation and AGNs is found in a statistical comparison of merger candidates and other galaxy samples. The assumed nature of precursor galaxies determines the assumed enhancement of far-IR luminosity caused by galaxy collisions. A model is presented which describes the properties of the Markarian galaxies in terms of enhanced OB star formation and different grain size distributions. The results of the investigation are shown to be consistent with a 'subdued' interpretation of merging galaxies with high luminosities.

The relative spatial distributions of emission-line galaxies (ELGs) and normal galaxies that lie in the sky area covered by the 'Slice' survey (de Lapparent et al., 1986) are considered. ELGs follow the same spatial distribution as found for the Slice galaxies, with the exception that they avoid the Coma cluster. It is pointed out that although the present ELGs are not shown to occur in regions of very low density, the luminosity distribution of the sample is such that luminosity/mass-dependent effects on the spatial distribution would not be noticeable.

A catalog of Markarian galaxies is presented which tabulates redshifts, spectral and morphological classifications, magnitudes, infrared and radio flux densities, and over 600 references to available data published before January 1, 1986. Redshifts are now available for 1228 objects with strong ultraviolet continua, and follow-up spectroscopic and photometric observations of Markarian galaxies have provided classifications of 115 Seyfert 1, 43 Seyfert 2, and 137 starburst and H II-type galaxies. After a description of the Markarian survey and the current catalog, a summary of the general results obtained from the data is presented. A preliminary study of the infrared properties of Markarian galaxies as measured by IRAS reveals a number of interesting results, including the existence of a sample of elliptical and lenticular galaxies with appreciable infrared emission. 450 references.

Interference filter images and long-slit spectroscopy are presented which show that much of the brighter filamentary gas in the Crab Nebula is involved in large structures consisting of a nearly pure helium band or torus across the neutron star and bipolar, helium-rich lobes. It is inferred that the SN precursor may have initially had a mass of 20-30 solar masses, and that the strongest forbidden Ni II emission coincides with regions of relatively low helium abundance in the north-east part of the nebula. The results support a scenario in which interaction and mixing occurs between an ambient interstellar cloud and material produced in the SN. 51 refs.

Presentation d'observations CCD optiques et radio a synthese d'ouverture de la galaxie a noyau double Mkn 266 (NGC 5256). Cette radiogalaxie est en fait constituee de 3 sources continuum non thermique. On suppose que l'emission synchrotron est stimulee par la collision de deux galaxies dont les disques entrent en coalescence